Telephone-exchange system.



F. V. YOUNG.

TELEPHONE EXCHAMSE SYSTEM. APPLICATION FILED FEB. 17. I917.

1,251,728. Patel lted Jan. 1, 1918.

UNITED STATES PATENT OFFICE.

FREDERICK v. YOUNG, or NEWARK, NEW JEasEY, Assre o T O. WESTERN ELEcrEIc COMPANY, INCORPORATED, on NEW YORK, N. Y., A CORPORATION on NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Jan. 1, 1918.

Application filed February 17, 1917. Serial No. 149,215.

To all whom it may concern:

Be it known that I, FREDERICK V. YOUNG, a citizen of the United States, residing at Newark, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Telephone-EX- change Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to such systems which employ automatic ringing for signaling purposes and which are provided with trunk lines extending to private branch exchanges, chief operators desks and like positions. I

The object of this invention is to preven the usual objectionable and disagreeable click in the answering operators receiver when a call over the trunk to which a source of ringing current is connected is being answered.

In accordance with a feature of this invention, when an operator answers the call by actuating a listening key, a quick-operating and slow-releasing relay is operated to disable the answering operators receiver before the tripping circuit for the ringing current is closed and to maintain the receiver, disabled until after the ringing current has been cut off and talking current substituted therefor. I This invention is illustrated in the accompanying drawing in which all apparatus is shown in its normal and unactuated condition.

There is shown in the drawing a telephone exchange system containing one embodicircuit A located at one section C of a switchboard, and a trunk circuit B extending from this section C to a desk operators position D at which there is a signaling device, a listening key andan operators telephone set, It is believed that this invention will be fully understood froma description of the operation of the system shown in the drawing and it will be so described.

The operator at section C, desiring to signal the desk operator 1), inserts a plug5 into a jack 6, whereupon lamp 7 will be lighted and relay 8 operated. The operation of relay 8 causes the actuation of a ringing relay 9 over a circuit from battery through resistance 10, winding of ringing relay 9, normal contact of relay 11, contact of tripping relay 12, and the closed contact of relay 8 to ground. The operation of relay 9 connects a source ofringing current 15 tothe trunk circuit B, causing the operation of relay 16 over a circuit from the source of ringing current 15 through the winding of tripping relay 12, lower alter- .nate contact of ringing relay 9, ring contacts of the plug a and jack 6,-contact 4 of listening key 18, condenser 17, loWerWinding of relay 16, tip contacts of jack 6 and plug 5, and upper alternate Contact ofringing relay '9 to ground. The operating winding of relay 16 is of high impedance so that the tripping relay 12 is not actuated when in circuit with relay 16. Relay 16 upon being actuated is locked up over a circuit from battery throughthe two contacts of relay 16 in series, the upper winding thereof, and contact?) of listening key 18 to ground. The lamp 19is lighted upon the actuation of relay 16 to furnish a signal to the desk operator, and remains lighted until the desk operator actuates the listening key 18. The ringing current also remains connected to the trunk circuit until the actuation of the listening key by the desk operator.

The desk operator, upon observing. the lighted condition of lamp 19, actuates the listening key, causing the following, operations in the order named. ment of this system, and comprising a cord 1. Opens contact 3 in thelocking circuit of relay 16, causing the release thereof and the eft'a'cement of lamp 19.

2. Closure of contact 27, causing the operation of a quick operating and slow-releasing relay 25 which short-circuits the answering operators receiver 29,0f the answering operators telephone set.

8. The closure of contacts 10 and 41; connecting relay 26 across the tip and ring conductors of the trunk circuit. Trippingrelay 12 and relay 26 thereupon operate. A The relay 9. Current from the battery in the cord circuit A is thereupon substituted for ringing current over the trunk. Relay 26 operates at the same time tripping relay 12 operates, opening the circuit of relay 25.

4. The closure of contact 42 connecting the answering operators telephone set to the trunk circuit. Since relay 25 is slow in re leasing, the operators telephone set is connected with the trunk circuit before the short circuit is removed from the receiver thereof.

When ringing relay 9 released, supervisory relay 30 is operated over a circuit from battery through winding 32 of repeating coil 33, winding of supervisory relay 30, lower normal contact of ringing relay 9, ring contacts of the plug 5 and jack 6, contact 40 of listening-key 18, winding of relay 26, contacts 41 and 12 of listening key 18, tip contacts of jack 6 and plug 5, upper normal contact of ringing relay 9, and winding 37 of repeating coil 33 to ground. The operation of supervisory relay 30 places resistance 10 in parallel with the lamp 7, which is thereby eifaced, indicating to the operator at the section or position C that the desk operator D has answered. It will be noted that relay 26, after being operated by current from source 15, remains operated by current from battery in the cord circuit, thereby maintaining the circuit of relay 25 open while the listening key is in its actuated position. Relay 26, therefore, serves as an impedance and holding coil.

From the above description, it will be readily seen that a system embodying the present invention permits of the tripping of the ringing current and the connection of battery current to the trunk circuit while the answering operators receiver is entirely out of the circuit, thereby avoiding in the answering operators receiver the disagreeable clicks usually attending the operation of tripping the ringing current. It will also be seen that by employing relay 26 as an impedance and holding coil, the calling sub- 'scriber connected to the other end of cord phone switchboard to a second board, means at one of said boards for applying ringing current over said trunk to the other board, an operators telephone set at said other board, a switch thereat actuated by the operator for connecting the operators telephone set to the trunk and for disconnecting the ringing current from the trunk, means for disabling the receiver of the operators telephone set during the period in which ringing current is being removed, and a relay connected with and operated over the trunk while the switch is actuated to render and maintain the disabling means ineffective after ringing current has been removed.

2. A telephone exchange system comprising a trunk circuit extending from one telephone switchboard to a second board, means at one of said boards for applying ringing current over said trunk to the other board, an operators telephone set at said other board, a switch thereat actuated by the operator for connecting the operators telephone set to the trunk and for disconnecting the ringing current from the trunk, a relay for disabling the receiver of the operators telephone set during the period in which ringing current is being removed, an operating circuit for the relay completed by the actuation of the switch, and a relay bridged across and operated over the trunk while the switch is actuated to open the operating circuit of and to maintain the first mentioned relay deenergized after ringing current has been removed.

3. A telephone exchange system comprise ing a trunk circuit extending from one telephone switchboard to a second board, means at one of said boards for applying ringing current over said trunk to the other board, an operators telephone set at said other board, a switch thereat actuated by the operator for connecting the operatorstelephone set to the trunk and for disconnecting the ringing current from the trunk, a slow releasing relay tor disabling the receiver of the operators telephone set during the period in which ringing current isbeing removed, an operating circuit therefor completed by the actuation of the switch, and a relay bridged across the trunk by the actuation of the switch and energized while the switch re mains actuated to open the operating circuit of and to maintain the slow releasing relay deenergized after ringing current has been removed.

V 1. A telephone exchange system comprising a trunk circuit extending from one tele phone switchboard to a second board, means at one of said boards for applying ringing current over said trunk to the other board, an operators telephone set at said other board, a switch thereat actuated by the operator for connecting the operators telephone set to the trunkand for disconnecting ringing current from the trunk, means for disabling the receiver of the operators telephone set during the period in which ringing current is being removed and a relay bridged across the trunk by the actuation of the switch and energized While the switch remains actuated to maintain the disabling my7name this 16th day of February, A. D. 191

FREDERICK V. YOUNG.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

